JSON Archiv Proxy for CSS

Table of Content

The JSON archive proxy for Control System Studio is a simple tool that
can be used in combination with any archive reader for CSS in order to
simplify the archive configuration.

The archive proxy consists of two components: The JSON archive server can
expose any archive reader via a simple protocol based on HTTP and JSON.
The JSON archive reader in turn connects to an instance of the JSON
archive server and makes its archives available in CSS.

The JSON archive proxy offers two advantages over a direct use of an
archive reader in CSS. First, the reader is light-weight and does not
depend on the structure of the database actually storing the data. Thus
the archive implementation can be upgraded (including changes in the
database structure) without having to update all instances of CSS that
access the archive. It is sufficient to update the archive reader
plugins installed in the JSON archive server. Second, the JSON archive
proxy can be used in environments where the database servers are behind a
firewall and direct access to the databases is not desired for security
considerations. With the JSON archive proxy, the JSON archive server is
installed in the same network that is accomodating the database servers
(the archive server can even run on the same machine as the database
server) and only a single port has to be opened for allowing the
communication between archive server and reader. As the protocol is
based on HTTP, a HTTP reverse proxy can be used for adding extra
security layers (e.g. SSL).

Version 3.x and Newer

Since version 3.x, the JSON Archive Proxy components are distributed
through a P2 repository (Eclipse update site). You can find the URL
of the P2 repository for the respective version in the
Download section.

Please refer to the documentation of the respective release for detailed
installation instructions.

Version 2.x and Older

Using the JSON archive proxy is very simple. It is enough to copy the
JSON archive reader plugin to the CSS distribution's plugins directory
and copying the plugins of the underlying archive reader (e.g. for the
Cassandra Archiver or
RDB Archiver)
to the plugins directory of the JSON archive server.

More detailed instructions can be found in the README.txt file in the
binary distribution of the JSON archive proxy.

This program and the accompanying materials are made available under the
terms of the
Eclipse Public License v1.0.
By downloading the software you agree to be bound the the terms of this license.
In particular, you have to agree to sections five (“NO WARRANTY”) and
six (“DISCLAIMER OF LIABILITY”) before downloading the software.

Some files in the binary distribution have different copyrights and
licenses. Refer to the information provided in the package for
details about those copyrights and licenses.

Release 3.0.0 (March 28th, 2017):Changes:
This release of the JSON Archive proxy adds compatibility with CSS 4.3 and
4.4. It is not compatible with older versions of CSS.
The protocol has not changed, so this release is still compatible with all
earlier versions.
Starting with this release, there is no archive download any longer.
Instead, the software is provided through a P2 repository (Eclipse update
site).

Release 2.0.3 (July 25th, 2016):Changes:
This release of the JSON archive proxy fixes a problem that caused the
precision information of samples to be lost, resulting in only in the
integer part of floating-point samples being shown.
correctly in the CSS Data Browser.
This release should be compatible with CSS 3.2, 4.0, and 4.1.
It does not make any changes to the server component and thus the server
version contained in the archive remains at version 2.0.1.
The protocol has not changed, so this release is still compatible with all
earlier versions.

Release 2.0.2 (June 2nd, 2016):Changes:
This release of the JSON archive proxy fixes a problem that caused samples
with statistics information (minimum and maximum value) not to be displayed
correctly in the CSS Data Browser.
This issue was caused by the samples not implementing an interface that was
expected by the Data Browser code.
This release should be compatible with CSS 3.2, 4.0, and 4.1.
It does not make any changes to the server component and thus the server
version contained in the archive remains at version 2.0.1.
The protocol has not changed, so this release is still compatible with all
earlier versions.

Release 2.0.1 (August 27th, 2015):Changes:
This release of the JSON archive proxy fixes compatibility issues with CSS
4.1. It should be compatible with CSS 3.2, 4.0, and 4.1. It also fixes a
bug in the server component that caused most requests for samples to fail.
The reader component was not affected by this bug.
The protocol has not changed, so it is still compatible with versions
1.0.0 and 2.0.0.

Release 2.0.0 (July 14th, 2014):Changes:
This release of the JSON archive proxy uses the new PVManager API
introduced with CSS 3.2 instead of the old PV abstraction layer. The JSON
protocol is the same as for version 1.0 of the JSON archive proxy, thus
a 2.0 client (archive-reader plugin) can connect to a 1.0 server and
vice-versa. This way, old archive-reader plugins can be used with new
versions of CSS and old versions of CSS can use new archive-reader plugins.